Harmon PB 105 trouble with ignition

[iceguy4]

I had an ignition problem with my boiler last night. The pellet selection is reduced this late in the season, so I was testing out a cheap pellet I had rejected last season because ... I had trouble with ignition in a cold burn pot. I thought I'd give them a second chance this year but got similar results.

My friend and neighbor Jay Z is burning them successfully in his Fahrenheit furnace and likes them, but they just don't light quickly enough in the PB 105 if the burn pot is cold, IME.

Here is the post...
wil lanfear said...
Last spring through this fall I burned Fireside Ultras to heat my DHW usage, I'm now burning Vermont Wood Pellets. The first 3 dip switches, only these 3 to be concerned with, control the quanity of pellets fed into the burnpot at start up before ignition. From left to right I have mine set #1 off, #2 on, #3 on, off is the down position. I don't know what your factory settings are, I have mine set to feed a smaller amount of pellets into the burnpot prior to ignition, fires quicker with less smoke

 

[Mr._Graybeard]

Ice, I'll give it a look, but it's a lot easier for now to use a pellet that ignites more easily.

What's happening with my boiler is that the initial feed of pellets doesn't light and after a few minutes, when the ESP senses no heat, it seems to conclude that no pellets are in the pot. So it starts the ignition process again with a fresh feed of pellets. At this point last night, there was no sign whatsoever of combustion. The extra pellets make the fuel even harder to ignite, so it goes through the process again ... and again. Pretty soon the pot is full of pellets. What I would prefer to adjust is the time that elapses between the initial feed and the point where the control board determines ignition failure and starts feeding pellets again. During that stretch the auger runs in an abbreviated mode and feeds few, if any, pellets.

 

[iceguy4]

Does anyone know where the dip switches are. I tried to find mine ...to no avail...

 

[wil lanfear]

Does anyone know where the dip switches are. I tried to find mine ...to no avail...

The dip switches, looking at the controller, are at the very top near the center of the controller. They may be covered by a decal or a knockout plate if they aren't visable, my boiler was one of the first manufactured, mine were not covered.

 

[SmokeEater]

SmokeEater, I did try cleaning out the vent pipe and boiler. Nothing was too bad to begin with, really. The one thing that makes me think that it's not a draft issue is that the flame looks fine when I run it in manual mode. Would this be the case if it were an issue of ash build up?

I didn't notice a major change in the appearance of the flame when the boiler was "ashed" up. Can't answer you on this one, but would think that the weight of the ash on the combustion fan blades slowed the fan and therefore reduced the needed draft. The fan had to move a larger mass and so the motor would have been loaded instead of loafing. Along with more "friction" in the vent, cause the poor combustion problem I saw.

 

[wil lanfear]

I keep ending up with a burn pot full of unburned pellets. I've replaced the igniter and cleaned the exhaust, as well as the entire stove. The igniter does seem to get hot, but nothing burns. It's been suggested that maybe there is not enough voltage getting to the igniter. Any other thoughts or suggestions? Thank you

Prior to replacing the igniter, did you not see smoke? Was the igniter that you replaced faulty? Are you sure that you have the igniter cradle installed correctly after you replaced the igniter,I ask because it can be installed incorrectly? What are the 1,2,3 dip switch settings? A burnpot full of pellets prior to ignition is not a good thing for quick ignition.

 

[BRADLEY]

Prior to replacing the igniter, did you not see smoke? Was the igniter that you replaced faulty? Are you sure that you have the igniter cradle installed correctly after you replaced the igniter,I ask because it can be installed incorrectly? What are the 1,2,3 dip switch settings? A burnpot full of pellets prior to ignition is not a good thing for quick ignition.[/quote
The night before the boiler stopped working, the entire basement had filled with smoke. I was out and came home to it. The boiler was still working at that point. I just tested the old igniter and read about 50 ohms across it, so it wasn't bad to begin with. Not sure what you mean about the 123 dip switch settings

 

[wil lanfear]

The dip switches, from left to right 1,2,3 that I mention control the quanity of pellets entering the burnpot prior to ignition (startup only). These switches are located at the very top of the controller, about center, maybe they are covered with a decal, on my boiler they were not covered. Excessive pellets in the burnpot at startup creates a ton of smoke, delays ignition, explosive firing or maybe no ignition at all. Find the dip switches that I've mentioned, tell me the setting of each, 1-3. ( down is off )

 

[BRADLEY]

The dip switches, from left to right 1,2,3 that I mention control the quanity of pellets entering the burnpot prior to ignition (startup only). These switches are located at the very top of the controller, about center, maybe they are covered with a decal, on my boiler they were not covered. Excessive pellets in the burnpot at startup creates a ton of smoke, delays ignition, explosive firing or maybe no ignition at all. Find the dip switches that I've mentioned, tell me the setting of each, 1-3. ( down is off )

It looks like they are all in the down position.

 

[Former Farmer]

Here is a copy for the dip switches. The factory set 1-3 off (down).



Have you replaced the burn pot recently? I know with the new style burn pot, I had to set the dip switches differently.

My boiler is from 2008, has a finned igniter and a new style burn pot, I have the switches set at 1=off , 2=on, 3=off.

 

[BRADLEY]

Here is a copy for the dip switches. The factory set 1-3 off (down).

View attachment 127025

Have you replaced the burn pot recently? I know with the new style burn pot, I had to set the dip switches differently.

My boiler is from 2008, has a finned igniter and a new style burn pot, I have the switches set at 1=off , 2=on, 3=off.

Mine is also from 2008. I've never replace the burnpot, nor have I ever adjusted the settings on the dipswitch. 1-3 are all down though

 

[Former Farmer]

I've replaced the igniter and cleaned the exhaust, as well as the entire stove.

When you replaced the igniter, did you put the hood that the mounts the igniter to the bottom of the burn pot on the correct way? You need the opening towards the bottom and the flat plate towards the top, for the air to be forced through the igniter.

 

[BRADLEY]

When you replaced the igniter, did you put the hood that the mounts the igniter to the bottom of the burn pot on the correct way? You need the opening towards the bottom and the flat plate towards the top, for the air to be forced through the igniter.[/quote
I think so. I'll check. However, the old igniter wasn't bad. I didn't know how to test it until after I'd replaced it. I tested the proper amount of resistance. Pretty sure I installed it correctly though. I'm going to shut it down later (it's in manual mode right now) I'll take a look then.

 

[wil lanfear]

After you shut the boiler down to insure that the igniter cradle is installed correctly, position the dip switches, 1 down, 2 up, 3 down , these settings will reduce the quanity of pellets fed into the burnpot prior to ignition, meaning a quicker ignition, less smoke. These settings reduce the auger feed time 43 seconds less than factory default settings of all 3 down. Longer pellets feed less than short pellets, a short pellet will always overfeed the burnpot on startup unless the dip switches are reset to prevent this. If you change the settings to what I've mentioned and you still get a lot of smoke, slow ignition, you can try settings, 1 down, 2 up, 3 up. If you try these settings, make sure enough pellets are fed into the burnpot for ignition, pellets do not need to completly cover the igniter for ignition.

 

[BRADLEY]

After you shut the boiler down to insure that the igniter cradle is installed correctly, position the dip switches, 1 down, 2 up, 3 down , these settings will reduce the quanity of pellets fed into the burnpot prior to ignition, meaning a quicker ignition, less smoke. These settings reduce the auger feed time 43 seconds less than factory default settings of all 3 down. Longer pellets feed less than short pellets, a short pellet will always overfeed the burnpot on startup unless the dip switches are reset to prevent this. If you change the settings to what I've mentioned and you still get a lot of smoke, slow ignition, you can try settings, 1 down, 2 up, 3 up. If you try these settings, make sure enough pellets are fed into the burnpot for ignition, pellets do not need to completly cover the igniter for ignition.

Igniter was installed correctly (open side down) and switched the settings on the dipswitch with the same results. What's confounding is that the burnpot is getting hot! But the pellets just pile up on top of it, unburned.

 

[Former Farmer]

Did you check the flap in the air intake tube? Possibly stuck closed?

 

[BRADLEY]

Did you check the flap in the air intake tube? Possibly stuck closed?

No. That's opening. Would the boiler still operate in manual mode if draft was an issue?

 

[Former Farmer]

Once you start a fire, you would have some natural draft from the heat wanting to rise. This would have helped pull more air through the intake possibly.

Definitely sounds like an air flow problem.

Have you cleaned the ESP probe recently?

Did you ignite the boiler manually? I had one burn pot that would light better after it had been burned once after cleaning. It seemed that the ash covering the holes towards the top of the pot forced more air through the igniter and it would light quicker.

Have you checked all of your gaskets to make sure that they are in good condition? Possible air leak could cause enough of an issue so the unit isn't pulling enough air through the burn pot for ignition.

 

[BRADLEY]

Once you start a fire, you would have some natural draft from the heat wanting to rise. This would have helped pull more air through the intake possibly.

Definitely sounds like an air flow problem.

Have you cleaned the ESP probe recently?

Did you ignite the boiler manually? I had one burn pot that would light better after it had been burned once after cleaning. It seemed that the ash covering the holes towards the top of the pot forced more air through the igniter and it would light quicker.

Have you checked all of your gaskets to make sure that they are in good condition? Possible air leak could cause enough of an issue so the unit isn't pulling enough air through the burn pot for ignition.

I haven't checked all the gaskets, they are old I suppose. Haven't cleaned the ESP probe.

 

[BRADLEY]

I haven't checked all the gaskets, they are old I suppose. Haven't cleaned the ESP probe.

Would I definitely have one?

 

[Former Farmer]

Would I definitely have one?

I am assuming that you are referring to the ESP probe. Yes, it is mounted in the combustion fan housing on the back of the unit. It is the part that is held in with a 1/4" head self tapping screw on the bottom of the tube that your venting is connected to and has two wires coming out of the probe.

Be very careful when handling this probe as they are fragile. I use a brass brush or a toothbrush to clean mine off with. If you find that the probe does not want to pull out of the hole, this will be because it is covered in carbon buildup from not having been removed before.

 

[Former Farmer]

Does your unit have the pressure release plate on the front of the unit under the firebox opening? Check that one as well. It may have opened at some point and have something stuck to it.

 

[BRADLEY]

I am assuming that you are referring to the ESP probe. Yes, it is mounted in the combustion fan housing on the back of the unit. It is the part that is held in with a 1/4" head self tapping screw on the bottom of the tube that your venting is connected to and has two wires coming out of the probe.

Be very careful when handling this probe as they are fragile. I use a brass brush or a toothbrush to clean mine off with. If you find that the probe does not want to pull out of the hole, this will be because it is covered in carbon buildup from not having been removed before.

I will check that. Thanks

 

[Mr._Graybeard]

I talked to an Earth Sense tech about cleaning the ESP, and he recommended using a Scotchbrite pad.

Speaking of cleaning, I gave my boiler a good going over yesterday -- brushed out and leaf-blowered the vent, cleaned off the blower fan, cleaned the ESP. Ignition is now much faster and pellets are "popcorning" nicely during the burn.

 

[wil lanfear]

Igniter was installed correctly (open side down) and switched the settings on the dipswitch with the same results. What's confounding is that the burnpot is getting hot! But the pellets just pile up on top of it, unburned.

Need to determine the quanity of pellets in the burnpot prior to ignition. First, shut down the boiler, clean out the burnpot of all pellets, close it back up, power the boiler on, as soon as it stops feeding pellets, prior to a lot of smoke, open the firebox door, power down the boiler, swing open the pellet storage bin so you can see the quanity of pellets in the burnpot. If the quanity of pellets in the burnpot is completely covering the area where the igniter is located, to many pellets are being fed at startup. Ideally, the pellet level should be just so they are starting to cover the igniter fins. After you have performed this test, don't forget to empty the burnpot prior to starting again.